GDP-32
II
INSTRUCTION MANUAL
May 2002 Section 6, Page 20
MANUALLY TRIM THE XMT
In extreme cases, the frequency difference between the two oscillators is too large to adjust out
electronically. In this case, manually trim the oscillator on the XMT-32 using a plastic trimming
tool or a small, insulated, flat-bladed screwdriver.
NOTE: The GDP-32
II
crystal adjustment potentiometer is not externally accessible. It is
unlikely that a customer would need to trim both oscillators.
There are approximately 70 coarse divisions for crystal adjustment of the GDP-32
II
. Before
adjusting the trim pot in the XMT-32, set the coarse adjustment on the GDP-32
II
to mid-range
using the following procedure:
Set the Crystal adjustment on the GDP-32
II
to Mid-Range:
1. Hold down one of the coarse adjustment keys (
Home
SELECT UP
or
SELECT DN
End
) until a rapid beep is
heard.
2. Press the opposite button (
Home
SELECT UP
or
SELECT DN
End
) 35 times (35 beeps) to set the coarse
adjustment to mid-range.
Manually trim the oscillator in the XMT-32:
1. Locate the OSC TRIM potentiometer adjustment screw on the panel of the XMT-32
(Figure 6.3.)
2. Make sure the meter function switch is in the PHASE position.
3. Using a plastic adjustment tool, turn the trim pot screw slowly in one direction and
observe the response on the XMT-32 meter.
4. If the needle motion slows down, the screw is being turned in the correct direction. If it
speeds up, turn it the other direction. Keep turning the screw until the needle movement
comes to a stop near the center of the meter.
5. Use the cursor control keys to adjust the frequency up or down slightly until the needle
roughly stabilizes near the center of the scale.
6. Using the fine adjustments on the GDP-32
II
, trim the frequency until the meter movement
halts. The oscillator is properly adjusted if the needle drifts less than the distance
between two meter marks over a 30 second interval.
7. If the PHASE needle does not stop after setting the crystal adjustment on the GDP-32
II
to
mid-range and manually trimming the XMT-32 oscillator, it is necessary to adjust the
crystals in either the GDP-32
II
or XMT-32. Consult Zonge Engineering before
attempting this procedure.
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